Analysis

Some Republicans despair of both Sen Ted Cruz's tactics and his ego. But he won't care - he has embraced Sen John McCain's description of him as a "wacko bird". Reading Dr Seuss' Green Eggs and Ham from the Senate floor can only elevate him from Daffy Duck to Roadrunner in the esteem of his public admirers.

Some Republicans think what he is doing is either pointless or dangerous. Pointless because this is not a classic filibuster - it stands no chance of actually killing the bill. Beyond that, it is odd, because the bill he is delaying couples paying the government's bills to defunding Obamacare.

That linkage is a core conservative tactic, which Mr Cruz himself agrees with. As Dr Seuss once wrote: "From there to here, from here to there, funny things are everywhere!"

That part will be removed from the version in the Senate, which on Wednesday held a procedural test vote on the matter, voting 100-0 to take up the House bill.

If, as expected, the Senate revises the House bill, the House will then have to decide whether to pass that bill or find a compromise with the Senate. They have until next Tuesday to avert a shutdown.

Sen Cruz, who began talking at 14:41 local time (18:41 GMT) on Tuesday, held the floor for 21 hours and 19 minutes, but had to yield at midday. It was the fourth-longest speech in Senate history.

Analysts say his marathon talk was a mainly symbolic gesture of defiance, rather than a filibuster - a tactic made famous by the 1939 Jimmy Stewart film, Mr. Smith Goes To Washington - as it could not hold up Senate proceedings.

Republicans sympathise with Sen Cruz's attempts to neuter the health law, which they label Obamacare.

But many deem his strategy to be politically unfeasible as long as Democrats control the Senate and White House.

With an eye on next year's midterm congressional elections, a number of Republicans are also concerned that voters might blame them for the havoc that results from any government shutdown.

Forgoing his cowboy boots for tennis shoes, Sen Cruz, a potential 2016 presidential candidate, railed all night against the Obama health law, calling it the country's "biggest jobs killer" and comparing his struggle to the fight against the Nazis, or the American Revolution.

'Bad haircuts'

To fill the time, the first-term senator covered a range of subjects, sharing with the largely empty chamber his penchant for the mini-hamburgers at fast-food chain White Castle; quoting from a reality television show, Duck Dynasty, as well as lyrics by country singer Toby Keith; and praising a recent speech by actor Ashton Kutcher on the value of hard work.

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Media captionTed Cruz: "Neville Chamberlain told the British people to accept the Nazis"

At one point on Tuesday night, Sen Cruz read bedtime stories - including the Dr Seuss favourite, Green Eggs and Ham - to his two young daughters, who he said were watching at home.

He also poked fun at fellow lawmakers: "Almost all of us are in cheap suits with bad haircuts. Who cares?"

Several Tea Party allies, including Senators Marco Rubio and Rand Paul, gave Sen Cruz some respite by taking to the lectern in his support.

Under the chamber's rules, Sen Cruz was allowed to give way to colleagues for long-form questions, but could not leave the floor or sit down while his speech was under way.

He took advantage of the break by strolling, stretching and leaning against desks.

But the top two Republicans in the Senate, Mitch McConnell and John Cornyn, refused to back him.